Los Angeles - Despite a call to boycott, the Hollywood war- movie spoof Tropic Thunder remained atop the North American box- office rankings for a third straight weekend with three-day ticket sales of 11.5 million dollars, according to preliminary studio estimates issued Sunday.

Ben Stiller's satire reached a total of 84 million dollars intake since its opening despite a call to boycott by handicapped association who charge the movie pokes fun at mentally handicapped people.

The film stars Stiller, Jack Black and Robert Downey Jr as three pampered actors filming a Vietnam War movie, only to be captured by real drug traffickers in the jungle.

Second place was held by the apocalyptic Babylon AD, an American- French production by director Mathieu Kassovitz which debuted at 9.7 million dollars.

The Batman adventure Dark Knight held third place on its seventh weekend, with 8.8 million dollars for the darkest version yet of the series. To date, the film has cashed in on 502.4 million dollars at the box office.

Along with the classic Titanic, it's only the second Hollywood movie to break the 500-million-dollar mark.

The House Bunny, starring Anna Faris as an ex-Playboy Bunny who takes the job of house mother in a university sorority, pulled in 8.3 million dollars for fourth place.

Jeffrey Nachmanoff's espionage thriller Traitor, an FBI story written by comedian Steve Martin, debuted in fifth place with 7.9 million dollars.

With the US holiday Labor Day on Monday, the summer cinema season will officially end. The weekend saw an overall drop in film-goers, testimony to extended weekend holiday travel and worries about Hurricane Gustav threatening New Orleans on Monday. (dpa)